Physics homework help (one question)

I have been having trouble with this one problem... If you could supply me with an answer and possibly a brief description of your methods I would be infinately in your debt:

A bus travels 320 km south along a straight path with an average velocity of 96 km/h to the south. The bus stops for 25 min, then it travels 230 km south with an average velocity of 70 km/h to the south. What is the average velocity for the total trip? Answer in units of km/h.